hAP ac2 powered through the USB port

I’ve made a Y cable to power a Huawei E8372 LTE USB modem separately since it was droping quite often and I presume it was because it was underpowered.
After conneting the Y cable to a 5V 3A power, to my surprise, the hAP ac2 powered on and it’s running fine for more than an hour.

Since all it’s fine I just wanted to check whether someone has experience in running the router from USB only for longer periods and whether it’s safe.

Thanks!

Silence.

Occasional bird chirping.

Most likely it will not handle any load above idle and could reboot.